Predicting the Contribution of Soil PMN to Total Corn N Uptake.

Many variables including organic matter, temperature, moisture, rainfall, and microbes can affect the mineralization of soil organic nitrogen (N). For this reason, interpreting timing and quantity of N mineralization that takes place is uncertain. Therefore, the objectives of this study are to determine the percent of potentially mineralizable nitrogen (PMN) used by the corn plant and use of PMN as an indicator of corn response to N fertilizer. In order to meet these objectives biomass of the thirteen way cover crop mixture was analyzed for N. Soil samples were taken in a grid formation across the field to interpret variation in the field with each plot being divided into two parts. Soil samples were then analyzed using an PMN test. Four different sidedress rates were applied to see how the soil test results react to applied N at the rates of 0, 47, 94, 141 kg of N/ha.

N test for the cover crop biomass resulted in 38-53 kg of N/ha. PMN test resulted in 187-284 kg of NH₄⁺N/HFS per week. End of season whole plant nitrogen analysis was performed allowing us to calculate N provided by the soil by subtracting the inorganic inputs from the total N taken up by the corn plant. This should allow us to assess how much PMN is accessible within the first year on this particular field. Yield data will be collected to examine whether PMN is relatable to yield across the field.

Data from this study could potentially increase the ability of farmers to adjust N management practices to the adoption of cover crops.